FRSC 1011H Chapter Notes - Chapter 5: Forensic Palynology, Product Rule, Buccal Swab
2 May 2018
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Physical Evidence
Identification, Comparison
● Two methods used by forensic scientists when examining physical evidence are
identification and comparison.
● Identification is the process of determining a substance’s chemical or physical
identity to the exclusion of all other substances.
● A comparison analysis determines whether a suspect or specimen and a
standard/reference specimen have a common origin.
● Evidence that can be linking to a common source with an extremely high degree
of probability is said to possess individual characteristics.
● The overall frequency of occurrence of an event, such as a match between two
substances, can be determined by multiplying together the frequencies of all
independently occurring instances related to that event. This is known as the
product rule.
Significance of Physical Evidence
● The value of class physical evidence lies in its ability to corroborate events with
data in a manner that is, as nearly as possible, free of human error and bias.
● As the number of objects linking an individual to a crime scene increases, so
does the likelihood of that individual’s involvement with the crime.
● A person may be exonerated or excluded from suspicion if physical evidence
collected at a crime scene is found to be different from standard/reference
samples collected from that subject.
Forensic Databases
● Forensic palynology involves the collection and examination of pollen and spores
connected with crime scenes, illegal activities, or terrorism. The microscope is
the principal tool used in the field of forensic palynology.
● The information gained from the analysis of pollen and spore evidence has many
possible uses. It can link a suspect or object to the crime scene or the victim,
prove or disprove a suspect’s alibi, include or exclude suspects, track the
previous whereabouts of some item or suspect, or indicate the geographical
origin of some item.
Document Summary
Two methods used by forensic scientists when examining physical evidence are identification and comparison. Identification is the process of determining a substance"s chemical or physical identity to the exclusion of all other substances. A comparison analysis determines whether a suspect or specimen and a standard/reference specimen have a common origin. Evidence that can be linking to a common source with an extremely high degree of probability is said to possess individual characteristics. The overall frequency of occurrence of an event, such as a match between two substances, can be determined by multiplying together the frequencies of all independently occurring instances related to that event. The value of class physical evidence lies in its ability to corroborate events with data in a manner that is, as nearly as possible, free of human error and bias. As the number of objects linking an individual to a crime scene increases, so does the likelihood of that individual"s involvement with the crime.
